Sulfur-containing dispersant and sulfide phosphor paste composition comprising the same

ABSTRACT

A sulfide phosphor paste composition comprising a sulfur-containing dispersant, and a fluorescent film prepared therefrom, are provided. The sulfur-containing dispersant has a dual head structure containing both a carboxyl group and a thiol group or a structure containing a thiol or thiophene group as a head group. An oligomeric sulfur-containing dispersant is also provided. Adsorption of the dispersant on the surface of the sulfide phosphor prevents aggregation of the phosphor particles, and thereby improves the dispersibility of the sulfide phosphor paste composition, the homogeneity of the phosphor in the paste composition, and the density of a film produced from the paste composition. Fluorescent films and display devices produced from the phosphor paste composition exhibit improved luminescent properties and excellent processability.

CROSS REFERENCE OF APPLICATION

This application is a divisional application of U.S. patent applicationSer. No. 11/410,766, filed Apr. 25, 2006, which claims priority to andthe benefit of Korean Patent Application No. 10-2005-0099064 filed onOct. 20, 2005 in the Korean Patent Office, the entire contents of whichare incorporated hereinto by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to compositions comprisingsulfur-containing dispersants. Specifically, the present inventionrelates to a sulfide phosphor paste composition comprising thesulfur-containing dispersants.

More particularly, the present invention relates to a compositioncomprising a sulfur-containing dispersant which has a structurecontaining both a carboxyl group and a thiol group as head groups or astructure containing a thiol or thiophene group as a head group, and asulfide phosphor paste composition comprising the sulfur-containingdispersant.

2. Description of the Related Art

In recent years, various display devices have been developed and widelyused as replacements for cathode ray tubes (CRTs). Such display devicesinclude flat panel displays (FPDs), e.g., liquid crystal displays,plasma display panels, electroluminescence displays and field emissiondisplays, and vacuum fluorescent displays. These display devicesnecessarily include fluorescent films and thus their luminescentproperties are dependent on the physical properties of the fluorescentfilms.

Sulfide phosphors, such as SrGa₂S₄, are widely used in the fields offield emission displays and cathodoluminescent displays. Fluorescentfilms for a variety of display devices are produced by preparing aphosphor paste composition comprising a phosphor, uniformly applying thephosphor paste composition to a given support, and drying the coatedsupport. Representative sulfide phosphor paste compositions are composedof a mixture of a solvent, a binder, and a sulfide phosphor, andoptionally comprise a dispersant for improving the dispersibility of thephosphor.

Such sulfide phosphor pastes tend to react with moisture or bechemically unstable in organic solvents (e.g., ethyl cellulose,terpineol and butyl carbitol acetate (BCA)) used in the preparation ofthe pastes. Some constituent components of sulfide phosphor pastecompositions may be completely dissolved in solvents, such as ethylcellulose, thus deteriorating the luminescent properties of displaydevices comprising fluorescent films produced from the compositions.

Where the viscosity reduction effect of dispersants in sulfide phosphorpastes is insufficient, the phosphors are inevitably used in relativelysmall amounts. Conversely, since an increased loading amount ofphosphors can cause an increase in the viscosity of sulfide phosphorpastes, the workability of fluorescent films prepared therefrom is poor,e.g., through formation of non-uniform fluorescent films, leading to lowyields and low productivity of the fluorescent films.

BRIEF SUMMARY OF THE INVENTION

Therefore, the present invention has been made in view of the aboveproblems of the prior art, and it is one object of the present inventionto provide a sulfur-containing dispersant capable of improving thedispersibility of particulate materials, including phosphors for use ina sulfide phosphor paste composition. It is another object of thepresent invention to provide a sulfide phosphor paste composition havingsuperior dispersibility and uniform physical properties.

It is another object of the present invention to provide ahigh-luminance fluorescent film having excellent processability.

It is yet another object of the present invention to provide a displaydevice comprising the fluorescent film.

In accordance with one aspect of the present invention for achieving theabove objects, there is provided a dispersion composition comprising asulfur-containing dispersant which has a dual head structure containingboth a carboxyl group and a thiol group, or a structure containing athiol or thiophene group as a head group; a particulate material; and anorganic solvent.

In accordance with another aspect of the present invention, there isprovided a sulfide phosphor paste composition comprising thesulfur-containing dispersant, a binder solution of an organic binder ina solvent, and a phosphor.

The phosphor paste composition may comprise 40-70% by weight of thephosphor and 0.1-3% by weight of the dispersant with respect to thephosphor powder, based on the weight of sulfur-containing dispersant,phosphor, and binder solution.

In accordance with another aspect of the present invention, there isprovided a fluorescent film formed from the phosphor paste compositionby a known process.

In accordance with yet another aspect of the present invention, thereare provided display devices, such as cathodoluminescent displays,liquid crystal displays and electroluminescence displays, which comprisethe fluorescent film.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a ¹H-NMR spectrum of a sulfur-containing dispersantsynthesized in Preparative Example 1 of the present invention;

FIG. 2 is a graph showing changes in viscosity according to the changesin the shear rate of phosphor paste compositions prepared in Examples 1to 3 and Comparative Example 1;

FIG. 3 is a graph showing changes in viscosity according to the changesin the shear rate of phosphor paste compositions prepared in Examples 4to 6 and Comparative Example 2;

FIG. 4A is a graph showing the luminescent properties of fluorescentfilms produced from phosphor paste compositions prepared in Examples 1and 2 and Comparative Example 1, and FIG. 4B is an enlarged partial viewof the graph shown in FIG. 4 a; and

FIG. 5A is a graph showing the luminescent properties of fluorescentfilms produced from phosphor paste compositions prepared in Examples 4and 5 and Comparative Example 2, and FIG. 5B is an enlarged partial viewof the graph shown in FIG. 5A.

DETAILED DESCRIPTION OF THE INVENTION

It will be understood in the following disclosure of the presentinvention, that when an element or layer is referred to herein as being“disposed on” another element or layer, the element or layer is in atleast partial contact with another element or layer, and there are nointervening elements or layers present. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

It will also be understood that, although the terms first, second,third, etc., may be used herein to describe various elements, processes,components, and/or layers, these elements, processes, components, and/orlayers should not be limited by these terms.

As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

The present invention will now be described in more detail.

A sulfur-containing dispersant as disclosed herein has a dual headstructure containing both a carboxyl group and a thiol group or astructure containing a thiol or thiophene group as a head group.

Specifically, the sulfur-containing dispersant comprises:

-   -   a compound of Formula 1

wherein

X is substituted C_(1˜200) alkyl, unsubstituted C_(1˜200) alkyl,substituted aryl, unsubstituted aryl, substituted arylalkyl, orunsubstituted arylalkyl,

-   -   R is H or methyl, and    -   P is a number from 1 to 10;

a compound of Formula 2

-   -   wherein 1 is a number from 1 to 20;

a compound of Formula 3CH₃(CH₂)₁₀CH₂—SH  (3);

a compound of Formula 4

or a combination comprising at least one of the foregoing compounds.

The sulfur-containing dispersant serves to improve the dispersibility ofa sulfide phosphor paste composition and permits an increase in theamount of the phosphor used while maintaining the viscosity of thephosphor paste composition at a constant level. Accordingly, a phosphorpaste composition comprising the sulfur-containing dispersant can beused to produce a fluorescent film or a display device having improvedluminance.

More specifically, the dispersant of Formula 1 can be represented byFormula 5 below:

wherein A is H or C_(1˜12) alkyl, m and n are each independently anumber from 1 to 20, and R is as defined in Formula 1.

In an exemplary embodiment, a dispersant of Formula 5 can be synthesizedby Reaction Scheme 1 below.

wherein BMA represents butyl methacrylate, TMSMA representstrimethylsilyl methacrylate, and m and n are as defined in Formula 5.

The sulfur-containing dispersant is useful in dispersion compositionsincluding sulfide phosphor paste compositions, but is not limitedthereto. The sulfur-containing dispersant can be added to any dispersionin which particulate materials, including nanomaterials such asinorganic nanoparticles, are dispersed in organic solvents. As usedherein, the term “nanomaterials” refers to particulate materials havingan average largest dimension of less than 1,000 nanometers (nm),specifically less than or equal to 500 nm, and more specifically lessthan or equal to 100 nm.

The present invention provides a phosphor paste composition comprising abinder solution and a phosphor, in addition to the sulfur-containingdispersant. The components other than the sulfur-containing dispersantmay be identical or similar to those used in conventional phosphor pastecompositions.

The binder solution includes a solvent and an organic binder. Theorganic binder functions to impart the viscosity of the phosphor pastecomposition after being dissolved in the solvent and to impart a bindingforce to the components after the phosphor paste composition is dried.Examples of organic binder resins that can be used in the presentinvention include, but are not limited to, acrylic polymers, styrenicpolymers, cellulose polymers, methacrylic ester polymers,styrene-acrylic ester copolymers, and polycarbonate polymers. Exemplarybinders include polystyrene, polyvinylbutyral, polyvinyl alcohol,polyethylene oxide, polypropylene carbonate, polymethylmethacrylate, andethyl cellulose. Combinations comprising at least one of the foregoingorganic binders may also be used. In an embodiment, cellulose polymers,such as for example ethyl cellulose, are preferred upon screen printing.

Taking into consideration the kinds of the phosphor and the organicbinder and the desired physical properties of the phosphor pastecomposition, the solvent used to prepare the binder solution can beselected from commercially available solvents and solvent mixtures.There is no particular restriction as to the kind of solvents that canbe used in the phosphor paste composition of the present invention, butit is preferred to use solvents that are volatilized at 150° C. orhigher.

Exemplary solvents include aromatic hydrocarbon compounds, e.g., tolueneand xylene, ether compounds, e.g., tetrahydrofuran and 1,2-butoxyethane,ketone compounds, e.g., acetone and methyl ethyl ketone, estercompounds, e.g., ethyl acetate, butyl acetate and butyl carbitol acetate(BCA), alcohol compounds, e.g., isopropyl alcohol, diethylene glycolmonobutyl ether, terpineol and 2-phenoxyethanol, and the like. Apreferred mixed solvent consists of terpineol and butyl carbitol acetatein a mixing ratio of 1:1 (w/w) to 1:2.5 (w/w) and preferably 1:1.7(w/w).

The binder solution includes 1.5-5% by weight of the organic binder andthe remainder of solvent, based on the combined weights of organicbinder and solvent. When the organic binder is used in an amount of lessthan 1.5% by weight, the amount of the solvent used is relatively largecompared to that of the organic binder, leading to a deterioration inthe coating quality of a fluorescent film. Meanwhile, when the organicbinder is used in an amount exceeding 5% by weight, the content of thesolvent is lower relative to the organic binder, thus reducing theamount of the phosphor used in the phosphor paste composition.

The phosphor used in the phosphor paste composition is not speciallyrestricted so long as it is used to prepare conventional phosphor pastecompositions. There is no restriction as to the kind and composition ofthe phosphor used in the present invention. Since the phosphor pastecomposition is mainly used to form fluorescent films for displaydevices, such as cathodoluminescent displays, liquid crystal displaysand electroluminescence displays, the kind and composition of thephosphor may be suitably selected according to the kind of excitationsources used in the display devices to excite the fluorescent filmsformed from the phosphor paste composition.

Specifically, as suitable phosphors, there can be used commerciallyavailable red, green and blue phosphors in the form of oxide solidsolutions that are currently used in display devices. A preferredphosphor is a mixture of oxides of barium, magnesium and aluminum in theform of a solid solution. Particularly, the dispersant can be added to apaste composition comprising a sulfide phosphor, such as SrGa₂S₄ orLa₂O₂S, to further improve the dispersibility of the composition.

More specifically, examples of sulfide phosphors that can be used in thepresent invention include, but are not limited to, SrS:Eu²⁺, SrGaS:Eu²⁺,SrGa₂S₄, SrCaS:Eu²⁺, ZnS:Ag⁺, CaS:Eu²⁺, ZnS:Cu⁺Al³⁺, ZnS:Ag⁺,Cl⁻,La₂O₂S, La₂O₂S:Eu³⁺, Y₂O₂S:Eu³⁺, CaAl₂S₄, and BaAl₂S₄:Eu²

The phosphor paste composition may further comprise at least oneadditive selected from plasticizers, leveling agents, lubricants,antifoamers and the like so long as the physical properties of thecomposition are not significantly adversely affected.

The phosphor paste composition may comprise 40-70% by weight of thephosphor and 0.1-3% by weight of the dispersant with respect to thephosphor powder, based on the weight of sulfur-containing dispersant,phosphor, and binder solution. When the content of the dispersant isless than 0.1% by weight, the amount of the phosphor used is relativelyincreased and thus the viscosity of the phosphor paste composition isnot maintained at a constant level. Also, when the content of thedispersant exceeds 3% by weight, the contents of the other componentssuch as the phosphor and organic binder decrease relative to thedispersant, and the physical properties of the phosphor pastecomposition may be adversely affected.

Typically, the amount of phosphor dispersed in a similar phosphor pastecomposition but using non-sulfur-containing dispersants can be less than40% by weight based on the weight of phosphor, dispersant, and bindersolution. However, use of the sulfur-containing dispersants disclosedherein can allow an increase in the phosphor content of the phosphorpaste composition to 40-70% by weight, based on the weight of phosphor,dispersant, and binder solution. The increased phosphor content in thephosphor paste composition can improve the luminance of a fluorescentfilm formed from the phosphor paste composition.

The phosphor paste composition can be prepared by adding the dispersantto the binder solution and adding the phosphor powder thereto.Specifically, the phosphor paste composition can be prepared inaccordance with the following procedure. First, an organic binder, suchas ethyl cellulose, is dissolved in a mixed solvent of butyl carbitolacetate and α-terpineol. Then, to the solution are added thesulfur-containing dispersant and an additive, such as an antifoamer or alubricant, followed by the addition of a phosphor. The resulting mixtureis homogeneously dispersed using a mill, such as a 3-roll mill, toprepare the final phosphor paste composition.

In another aspect, the present invention is directed to a fluorescentfilm produced from the phosphor paste composition. The fluorescent filmis produced by applying the phosphor paste composition to a support,such as glass or transparent plastic, to form a particular patternthereon and heating the coated support by drying and baking to removevolatiles (e.g., solvent) and harden the phosphor paste. The phosphorpaste composition desirably forms a uniform, low defectivity layer onthe support. Thus, in an embodiment, a fluorescent film comprises aphosphor layer comprising the phosphor, the organic binder, and thesulfur-containing dispersant, and the support, wherein the phosphorlayer is disposed on and in at least partial contact with the support.

The fluorescent film can be produced and patterned using knowntechniques, including but not limited to pattern screen printing,electrophoresis, photolithography, ink jet, and the like.

Since the fluorescent film produced from the phosphor paste compositioncomprising the sulfur-containing dispersant enables the use of a largeramount of the phosphor in proportion to the amounts of organic binderand sulfur-containing dispersant, the luminance is thereby improved,whereas any increase in viscosity is relatively limited and does notsignificantly adversely affect the coating properties and/or uniformityof the phosphor paste composition and any fluorescent film preparedtherefrom. Thus, the processability of the fluorescent film is improved.

The fluorescent film can be used for the fabrication of a variety ofdisplay devices, including cathodoluminescent displays, liquid crystaldisplays, electroluminescence displays, field emission displays andvacuum fluorescent displays. Display devices comprising the fluorescentfilm exhibit improved luminescent properties and uniform physicalproperties.

The present invention will be explained in more detail with reference tothe following examples illustrating preferred embodiments of the presentinvention. These examples are given for the purpose of illustration andare not to be construed as limiting the scope of the invention.

PREPARATIVE EXAMPLE 1 Preparation of Sulfur-Containing Dispersant of theFormula (6)

Methyl trimethylsilyl dimethylketene acetal (3.48 g, 20 mmol, Aldrich)as an initiator, tetrabutylammonium-3-chlorobenzoate (0.8 g, 0.2 mmol)as a catalyst, and purified acetonitrile (0.5 ml) were placed in a 50 mlround-bottom flask, and stirred using a magnetic bar for one hour. Tothe reaction solution was slowly added a solution of butyl methacrylate(BMA, 8.18 g, 57.5 mmol, Aldrich) and trimethylsilyl methacrylate(TMSMA, Aldrich) in purified THF (3 ml). The resulting mixture wasstirred for 2 hours. After the disappearance of the butyl methacrylateand trimethylsilyl methacrylate was confirmed by gas chromatography(GC), a solution (0.5 ml) of tetrabutylammonium-3-chlorobenzoate (0.8 g,0.2 mmol) in acetonitrile was added thereto. To the reaction solutionwas added a solution of 2-(methylthio)ethyl methacrylate (1.6 g, 10mmol) in purified THF (2 ml). After the resulting mixture was stirredfor 2 hours, the solvents were removed using a rotary evaporator. Theobtained residue was dissolved in methanol and refluxed at 70° C. for 3hours. The methanol was removed from the reaction solution using arotary evaporator. The obtained residue was dissolved in methylenechloride, washed with distilled water, and filtered. After the methylenechloride was removed from the filtrate using a rotary evaporator, theobtained residue was dried in a vacuum oven for 12 hours, yielding adispersant (9.2 g) as a viscous oil. The structure of the dispersant (6)was identified by ¹H-NMR spectroscopy (FIG. 1).

EXAMPLE 1

A commercially available SrGa₂S₄ powder (KX501A Kasei Optonix Ltd.,Japan) was used as a phosphor. The phosphor powder was dried in a vacuumat 130° C. for 24 hours before use

Separately, 0.51 g of ethyl cellulose as an organic binder was dissolvedin a mixed solvent of α-terpineol (4.61 g) and butyl carbitol acetate(7.68 g) to prepare a binder solution. The phosphor powder was added tothe binder solution, and then the sulfur-containing dispersant preparedin Preparative Example 1 was added thereto. The resulting mixture wasmilled to prepare a phosphor paste composition of the present invention.

EXAMPLES 2 AND 3

Phosphor paste compositions were prepared in the same manner as inExample 1, except that 1-dodecanethiol (1-dodecanethiol, Aldrich, USA)(Example 2) of Formula 3 and 3-dodecylthiophene (1-dodecanethiol,Aldrich, USA) (Example 3) of Formula 4 were used as dispersants.

COMPARATIVE EXAMPLE 1

A phosphor paste composition was prepared in the same manner as inExample 1, except that no dispersant was used.

EXAMPLES 4 TO 6

Phosphor paste compositions were prepared in the same manner as inExamples 1 to 3, respectively, except that a La₂O₂S powder (KX-681,Kasei, Japan) was used as a phosphor.

COMPARATIVE EXAMPLE 2

A phosphor paste composition was prepared in the same manner as inComparative Example 1, except that a La₂O₂S powder (KX-681, Kasei,Japan) was used as a phosphor.

EXPERIMENTAL EXAMPLE 1 Evaluation of Changes in Viscosity of PhosphorPaste Compositions

Changes in viscosity with increasing shear rates of the phosphor pastecompositions prepared in Examples 1 to 3 and Comparative Example 1 weremeasured, and the obtained results are shown in FIG. 2. The viscositywas measured using a viscometer (AR2000, Thermal Analysis, USA). Themeasurement was done using a #14 spindle at 24.5-25.5° C. for 30seconds. For comparison, changes in the viscosity of the phosphor pasteprepared in Comparative Example 1 were measured according to changes inshear rate, and the results are shown in FIG. 2.

The graph shown in FIG. 2 demonstrates that the phosphor pastecomposition of Example 1 using the sulfur-containing dispersant exhibitsdistinct viscosity reduction effect when compared to the phosphor pastecomposition prepared in Comparative Example 1.

These results suggest that the phosphor paste compositions comprisingthe dispersants permit the use of a larger amount of the phosphor, thusimproving the luminescent properties of fluorescent films produced fromthe compositions.

EXPERIMENTAL EXAMPLE 2 Evaluation of Changes in Viscosity of PhosphorPaste Compositions

Changes in viscosity with increasing shear rates of the phosphor pastecompositions prepared in Examples 4 to 6 and Comparative Example 2 weremeasured by the same procedure as described in Experimental Example 1.The results are shown in FIG. 3. The graph shown in FIG. 3 demonstratesthat the phosphor paste composition of Example 5 using thesulfur-containing dispersant exhibits distinct viscosity reductioneffect when compared to the phosphor paste composition prepared inComparative Example 2.

These results suggest that the phosphor paste compositions comprisingthe sulfur-containing dispersants permit the use of a larger amount ofthe phosphor, thus improving the luminescent properties of fluorescentfilms produced from the compositions.

EXPERIMENTAL EXAMPLE 3 Evaluation of Luminescent Properties of PhosphorPaste Compositions

Each of the phosphor paste compositions prepared in Examples 1 and 2 andComparative Example 1 was coated using a film applicator (BYK-Gardner®)to a thickness of 30 μm on a glass support. The coating layer was firedto 480° C. at a rate of 5° C./min. using a lamp to form a fluorescentfilm. The luminescent properties of the fluorescent film were evaluated.

The evaluation of the luminescent properties was conducted using aPhosphor of Emission and Decay Measurement System (an assembly of a VUVexcimer lamp (USHIO, Japan) and a vacuum chamber system (Motech vacuum,Korea)) under the following conditions:

-   -   Vacuum pressure: 3-10 torr    -   Light source wavelength: 146 nm    -   Wavelength range: 230-780 nm    -   Wavelength interval: 1 nm.

The results are shown in FIG. 4 a. FIG. 4 b is an enlarged partial viewof the graph shown in FIG. 4 a. For comparison, the luminescentproperties of the phosphor powder used in Example 1 were measured andthe obtained results are shown in the figures.

As shown in FIGS. 4 a and 4 b, the maximum luminescence intensity of thecompositions (Examples 1 and 2) prepared using the sulfur-containingdispersants is increased by 3.4% and 2.1%, respectively, compared tothat of the phosphor powder. In contrast, the maximum luminescenceintensity of the composition (Comparative Example 1) using no dispersantis decreased by 4.0%, compared to that of the phosphor powder. Theseresults show that the phosphor paste compositions comprising thedispersants exhibit improved luminescence intensity as compared toconventional phosphor paste compositions.

EXPERIMENTAL EXAMPLE 4 Evaluation of Luminescent Properties of PhosphorPaste Compositions

The luminescent properties of the phosphor paste compositions preparedin Examples 4 and 5 and Comparative Example 2 were evaluated by the sameprocedure as described in Experimental Example 3.

The results are shown in FIG. 5 a. FIG. 5 b is an enlarged partial viewof the graph shown in FIG. 5 a.

As shown in FIGS. 5 a and 5 b, the maximum luminescence intensity of thefluorescent films produced from the compositions (Examples 4 and 5)using the sulfur-containing dispersants is increased by 3.0% and 3.6%,respectively, compared to that of the phosphor powder. In contrast, themaximum luminescence intensity of the fluorescent film produced from thecomposition (Comparative Example 2) using no dispersant is decreased by2.8%, compared to that of the phosphor powder. These results show thatthe phosphor paste compositions comprising the dispersants improve theluminescence intensity of fluorescent films as compared to conventionalphosphor paste compositions.

Although the preferred embodiments have been disclosed for illustrativepurposes, those skilled in the art will appreciate that variousmodifications and variations are possible, without departing from thescope and spirit of the invention as disclosed in the appended claims.Accordingly, such modifications and variations are intended to comewithin the scope of the appended claims.

As apparent from the above description, the novel sulfur-containingdispersant has advantages that it improves the dispersibility of aphosphor paste composition and solves the problem of oxidation arisingfrom the use of organic solvents. Particularly, the sulfur-containingdispersant exhibits superior effects when it is used to prepare asulfide phosphor paste composition.

Since the phosphor paste composition comprising the sulfur-containingdispersant has improved dispersibility and constant viscosity, itpermits the use of a larger amount of a phosphor, thus enabling theformation of uniform fluorescent films having improved luminescentproperties. Therefore, according to the present invention, displaydevices, such as LCDs, having high luminance and excellentprocessability can be fabricated.

1. A fluorescent film comprising: a phosphor layer comprising aphosphor, an organic binder, and a sulfur-containing dispersant selectedfrom the group consisting of: a compound of Formula (1)

wherein X is substituted C_(1˜200) alkyl, unsubstituted C_(1˜200) alkyl,substituted aryl, unsubstituted aryl, substituted arylalkyl, orunsubstituted arylalkyl, R is H or methyl, and P is a number from 1 to10; a compound of Formula (2)

wherein 1 is a number from 1 to 20; and a combination comprising atleast one of the foregoing compounds; and a support; wherein thephosphor layer is disposed on and in at least partial contact with thesupport.
 2. A sulfur-containing dispersant represented by Formula 5:

wherein A is H or C_(1˜12) alkyl, m and n are each independently 1 to20, and R is H or methyl.